A new species of terrestrial isopod, Porcellio danieli sp. nov., (Oniscidea: Porcellionidae) is described from the southernmost Iberian Peninsula (province of Cádiz, Spain). The new species belongs to the ‘laevis-hoffmannsseggii’ systematic complex, with close affinities with other maghrebian-saharian representatives of the same genus. Their similarities and differences with other species of the group are discussed, and some species found in both southern Spain and northern Africa are listed.